Wireless communication device and radiation directivity estimating method

Abstract

A wireless communication device includes a circuit board to include an antenna element, an estimating unit to estimate a current distribution in at least a partial area on the circuit board, which is induced by power feeding to the antenna element, and a specifying unit to specify a radiation pattern associated with the current distribution estimated by the estimating unit as a radiation directivity of the circuit board.

What is claimed is: 
     
       1. A wireless communication device comprising:
 a circuit board to include an antenna element; 
 an estimating unit to estimate a current distribution based on current values which are generated by power feeding to the antenna element on the circuit board; and 
 a specifying unit to specify a radiation pattern indicating a directivity from the estimated current distribution on the circuit board on which the antenna element is disposed, by using pre-retained correspondence relation between current distribution patterns and radiation patterns. 
 
     
     
       2. The wireless communication device according to  claim 1 , further comprising a current detecting unit to detect a current on the circuit board,
 wherein the estimating unit estimates, as a present current distribution, any one of a plurality of previously-retained current distribution patterns on the circuit board by use of a current value detected by the current detecting unit, and 
 the specifying unit specifies, as the radiation directivity of the circuit board, the radiation pattern associated with the current distribution estimated by the estimating unit in the plurality of radiation patterns associated respectively with the plurality of previously-retained current distribution patterns on the circuit board. 
 
     
     
       3. The wireless communication device according to  claim 2 , wherein the current detecting unit are a plurality of current sensors which are disposed in a plurality of different positions on the circuit board and detect the respective current values in individual positions, and
 the estimating unit retains a plurality of current distribution patterns associated with correlations of the respective current values detected in the different positions on the circuit board, and estimates any one of the plurality of current distribution patterns as the present current distribution by use of results of comparisons between the plurality of current values detected by the plurality of current sensors. 
 
     
     
       4. The wireless communication device according to  claim 2 , wherein the current detecting unit detects the currents in positions in which to make identifiable the respective current distribution patterns where the radiation patterns on the circuit board change corresponding to the plurality of current distribution patterns on the circuit board that are calculated by electromagnetic field simulations on the assumption that a living body is in contact with a lower surface of the circuit board and exists in a predetermined position from each side other than the lower surface of the circuit board. 
     
     
       5. The wireless communication device according to  claim 2 , wherein the current detecting unit, when the antenna element is installed in an edge area on the circuit board, detects the currents in a plurality of different positions in the other edge area, spaced-apart from the antenna element, on the circuit board. 
     
     
       6. A radiation directivity estimating method to estimate radiation directivity from a circuit board which includes an antenna element, the method including:
 estimating a current distribution based on current values which are generated by power feeding to the antenna element on the circuit board; and 
 specifying a radiation pattern indicating a directivity from the estimated current distribution on the circuit board on which the antenna element is disposed, by using pre-retained correspondence relation between current distribution patterns and radiation patterns. 
 
     
     
       7. The radiation directivity estimating method according to  claim 6 , further including detecting a current on the circuit board,
 wherein the estimating the current distribution includes estimating, as a present current distribution, any one of a plurality of previously-retained current distribution patterns on the circuit board by use of a detected current value, and 
 the specifying the radiation pattern includes specifying, as the radiation directivity of the circuit board, the radiation pattern associated with the estimated current distribution in the plurality of radiation patterns associated respectively with the plurality of previously-retained current distribution patterns on the circuit board. 
 
     
     
       8. The radiation directivity estimating method according to  claim 7 , wherein the detecting the current includes detecting the respective current values in the plurality of different positions on the circuit board, and
 the estimating the current distribution includes estimating any one of the current distribution patterns, as the present current distribution, associated with the correlation of the respective current values detected in the different positions on the circuit board from within the plurality of previously-retained current distribution patterns. 
 
     
     
       9. The radiation directivity estimating method according to  claim 7 , wherein the detecting the current includes detecting the currents in positions in which to make identifiable the respective current distribution patterns where the radiation patterns on the circuit board change corresponding to the plurality of current distribution patterns on the circuit board that are calculated by electromagnetic field simulations on the assumption that a living body is in contact with a lower surface of the circuit board and exists in a predetermined position from each side other than the lower surface of the circuit board. 
     
     
       10. The radiation directivity estimating method according to  claim 7 , wherein the detecting the current includes, when the antenna element is installed in an edge area on the circuit board, detecting the currents in a plurality of different positions in the other edge area, spaced-apart from the antenna element, on the circuit board.